The invention relates to an arrangement for adjusting the cylinders in rotary printing presses, and in particular for adjusting the distance of two cylinder axles between two corresponding cylinders for processing of sheet-like and web-like material with different paper thicknesses.
A modification of the cylinder axles distance must be obtained for processing different paper thicknesses in order to maintain constant the printing pressure at each paper thickness.
In known rotary printing presses, roller rings are arranged at the front ends of the two cylinders. The rollers rings are kept under a certain pre-tension which is higher than the printing pressure and roll on each other in pairs. In these arrangements, a modification of the cylinder axles distance, and of the printing gap between the cylinders is only possible through modification of the printing layer thickness. This, however, is disadvantageous as a change of the printing layer prior to each new application is uneconomical.
The DD-PS No. 92,943 discloses an arrangement for changing the printing gap in which the barrel rings of smaller diameter are supported by the end faces of the cylinder via a roller ring which in vicinity of a cylinder center by means of an eccentric approximately maintains constant the pre-tension of the barrel rings parallel to the change of the printing gap via a correcting gearing.
This arrangement has, however, the disadvantage that the forces introduced outside of the cylinder centers are essentially larger than the required pre-tension, and consequently leads to an unnecessary loading of the structural unit. Moreover, a modification of the printing gap does not guarantee a uniform printing pressure.